1. Field of the Invention
This invention relates generally to an apparatus for receiving a super high frequency (SHF) signal and more particularly to an SHF receiver for receiving SHF broadcast signals from, for example, a broadcast satellite.
2. Description of the Prior Art
Generally, as shown in, for example, FIG. 1, an SHF receiver receiving an SHF broadcast signal from a broadcast satellite (not shown) consists of an antenna 1, an outdoor unit 2 installed in the outside of a house together with the antenna 1 to frequency-convert an electrical wave of an SHF band that is received by the antenna 1 to an electrical wave of a UHF band and to amplify the same, a coaxial cable 3, an indoor unit 4 and a television receiver 5 both installed inside the house. The indoor unit 4 is supplied with the signal that is frequency-converted to the ultra high frequency (UHF) band signal from the outdoor unit 2 through the coaxial cable 3 and derives a video signal and an audio signal that are supplied to the television receiver 5.
By the way, there are considered, for example, a low power broadcast (receiving frequency is 11.7 to 12.2 GHz) and a high power broadcast (receiving frequency is 12.2 to 12.7 GHz) for the SHF broadcast.
However, in the above SHF receiver, if the local oscillation frequency in the outdoor unit 2 is not changed over, the indoor unit 4 must correspond to the frequency band of 1000 MHz in view of frequency and it becomes extremely difficult to realize the indoor unit 4 in circuitry standpoint.
Accordingly, in order to receive two broadcast different in frequency band by the indoor unit 4 of simple construction, the local oscillation frequency in the outdoor unit 2 must be changed over.
To change over the local oscillation frequency in the outdoor unit 2, it may be considered that in addition to the coaxial cable 3, for example, there is provided independently a local oscillation frequency control cable that is extended from the indoor unit 4 to the outdoor unit 2 and the switching of the local oscillation frequency is controlled therethrough. However, it is undesirable that a plurality of cables are provided between the outdoor unit 2 and the indoor unit 4 in signal transmission standpoint. Also, the plurality of cables cause the number of the terminals of the outdoor unit 2 to be increased, which is not preferable in air-tight state standpoint to avoid the leakage of, for example, rainwater into the outdoor unit 2.